The Chocolate And Wrappers Problem

Here’s an interesting mind twister:
A chocolate costs 1 rupee each. You can also exchange 3 wrappers for a chocolate. If you have 15 rs, how many chocolates can you get??
I posted the question on my facebook wall and instantly started getting lots of answers from friends. To my surprise many of them got it wrong. I even had to explain the logic to some of them before they could understand why the answer was 22.

Logic:
You can exchange the 15 wrappers for 5 chocolates. Now you have 15 chocolates without wrappers and 5 with wrappers.
Now exchange three more wrappers for a chocolate. Now you have 18 chocolates without wrappers and 2+1 chocolates with wrappers.
Again exchange the 3 wrappers for one more chocolate. Now you have 21+1=22 chocolates.

Here’s an interesting variation of the problem.You can buy 5 chocolates for rs.4 but only one with re.1 . You have 50 bucks in your pocket.As before, you can exchange 3 wrappers for a chocolate. What is the max number of chocolates you can have and the number of wrappers you will have in the end ??

In fact, the question can be used as a programming problem. Here’s the source code in php. Even if you don’t know php, the logic is clear enough for anyone to understand. <?php
$chocolate = 0;
$wrapper = 0;
$money = 50;